JE pistons in unsleeved H22A1 block

[bradboy]

I was told that unlike the H22A4, the H22A1 has to be sleeved for use with forged pistons, is this true? Has anyone used forged pistons in an unsleeved H22A1 block with out any probs?

[inferno]

This is not true. Your motor has a "closed deck" design and is a stronger motor than the later H22 motors, which are an "open deck" design. Even those motors don't need to be re-sleeved to run boost, but it is recommended that they either get a block guard or be resleeved if lots of boost is planned to make sure that the weak part in the block (top if the cylinders in an open deck design) doesn't fail under the high stress that a turbo puts on a motor.

[fritz_269]

Originally posted by inferno
it is recommended that they either get a block guard or be resleeved if lots of boost is planned to make sure that the weak part in the block (top if the cylinders in an open deck design) doesn't fail under the high stress that a turbo puts on a motor.

Just curious - has anyone actually seen a FI Honda motor fail at the open deck? Or is everyone doing the block guard with a 'better safe than sorry' attitude?

I have seen turbo motor fail at the block, but it's always been on the thrust side of the cylinder sleeve, never at the deck.

[Someguy]

Originally posted by fritz_269

I have seen turbo motor fail at the block, but it's always been on the thrust side of the cylinder sleeve, never at the deck.

But is that wear the failure "happened" or just where the rod ended up poking out?

BTW, haven't seen you around forever Inferno! Welcome back.

[bradboy]

Originally posted by bradboy
I was told that unlike the H22A4, the H22A1 has to be sleeved for use with forged pistons, is this true? Has anyone used forged pistons in an unsleeved H22A1 block with out any probs?

Guys I am really refering to the theory that forged pistons are not compatible with the 'nicosil' coating used in Honda's H22A block.

[fritz_269]

Originally posted by Someguy
But is that wear the failure "happened" or just where the rod ended up poking out?

Good question! Kind of hard to tell. But there was no apparent damage in the area of the open deck.

I was just wondering if anyone had actually seen a failure of an open deck. It occured to me that peak pressure isn't really reached until the piston is well down in the cylinder - where there is much less support for the sleeve than there is at the open deck. i.e. Why does it matter that that top 1/4" of the sleeve be reinforced when there are several inches of unreinforced sleeve halfway down the cylinder where the peak pressure occurs.

Could it be for detonation safety? How far past TDC does bad detonation occur?

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bradboy - I've never heard that Nikasil (or Kanisil or Elnisil) is incompatible with forged pistons. I think the ITR uses Nikasil & forged pistons in stock form. Just be careful with break-in if you use chrome rings (which I wouldn't recommend for a street engine anyway!)

[inferno]

I have seen only one failure at the top of the sleeve and that was on a nitrous motor. But the better safe than sorry adage is about right....I have heard of several more, but only seen one. I am sure that they wouldn't have produced the product if it wasn't a danger in high boost situations.